Earth-boring tools including rotatable cuting element assemblies and related methods of forming and using the same

ABSTRACT

An earth-boring tool comprises a tool body and a cutting element assembly. The assembly comprises a cutting element including a table of polycrystalline hard material secured to a substrate. The table has a front cutting face and a central axis extending through a center of the front cutting face. The assembly also comprises a sleeve having a cavity formed therein and a central axis extending therethrough. A positioning feature and the cutting element may be disposed within the cavity. The positioning feature is configured to radially offset the central axis of the table from the central axis of the sleeve. The cutting element is rotatable about the central axis of the table within the cavity of the sleeve, and the cutting element and positioning feature are rotatable within the cavity of the sleeve such that the central axis of the table revolves about the central axis of the sleeve.

FIELD

Embodiments of the present disclosure relate generally to devices and methods involving rotatable cutting elements for earth-boring tools used in earth boring operations and, more specifically, to rotatable cutting elements for earth-boring tools configured to rotate in order to alter an exposure of a cutting edge of the cutting element relative to an adjacent surface of the earth-boring tool to which a cutting element assembly is mounted, to earth-boring tools so equipped, and related methods.

BACKGROUND

Wellbores are formed in subterranean formations for various purposes including, for example, extraction of oil and gas from the subterranean formation and extraction of geothermal heat from the subterranean formation. Wellbores may be formed in a subterranean formation using a drill bit, such as an earth-boring rotary drill bit. Different types of earth-boring rotary drill bits are known in the art, including fixed-cutter bits (which are often referred to in the art as “drag” bits), rolling-cutter bits (which are often referred to in the art as “rock” bits), diamond-impregnated bits, and hybrid bits (which may include, for example, both fixed cutters and rolling cutters). The drill bit is rotated and advanced into the subterranean formation. As the drill bit rotates, the cutters or abrasive structures thereof cut, crush, shear, and/or abrade away the formation material to form the wellbore. A diameter of the wellbore drilled by the drill bit may be defined by the cutting structures disposed at the largest outer diameter of the drill bit.

The drill bit is coupled, either directly or indirectly, to an end of what is referred to in the art as a “drill string,” which comprises a series of elongated tubular segments connected end-to-end that extends into the wellbore from the surface of earth above the subterranean formations being drilled. Various tools and components, including the drill bit, may be coupled together at the distal end of the drill string at the bottom of the wellbore being drilled. This assembly of tools and components is referred to in the art as a “bottom hole assembly” (BHA).

The drill bit may be rotated within the wellbore by rotating the drill string from the surface of the formation, or the drill bit may be rotated by coupling the drill bit to a downhole motor, which is also coupled to the drill string and disposed proximate the bottom of the wellbore. The downhole motor may include, for example, a hydraulic Moineau-type motor having a shaft, to which the drill bit is mounted, that may be caused to rotate by pumping fluid (e.g., drilling mud or fluid) from the surface of the formation down through the center of the drill string, through the hydraulic motor, out from nozzles in the drill bit, and back up to the surface of the formation through the annular space between the outer surface of the drill string and the exposed surface of the formation within the wellbore. The downhole motor may be operated with or without drill string rotation.

A drill string may include a number of components in addition to a downhole motor and drill bit including, without limitation, drill pipe, drill collars, stabilizers, measuring while drilling (MWD) equipment, logging while drilling (LWD) equipment, downhole communication modules, and other components.

In addition to drill strings, other tool strings may be disposed in an existing well bore for, among other operations, completing, testing, stimulating, producing, and remediating hydrocarbon-bearing formations.

Cutting elements used in earth boring tools often include polycrystalline diamond compact (often referred to as “PDC”) cutting elements, which are cutting elements that include so-called “tables” of a polycrystalline diamond material mounted to supporting substrates and presenting a cutting face for engaging a subterranean formation. Polycrystalline diamond (often referred to as “PCD”) material is material that includes inter-bonded grains or crystals of diamond material. In other words, PCD material includes direct, intergranular bonds between the grains or crystals of diamond material.

Cutting elements are typically mounted on the body of a drill bit by brazing. The drill bit body is formed with recesses therein, commonly termed “pockets,” for receiving a substantial portion of each cutting element in a manner which presents the PCD layer at an appropriate back rake and side rake angle, facing in the direction of intended bit rotation, for cutting in accordance with the drill bit design. In such cases, a brazing compound is applied between the surface of the substrate of the cutting element and the surface of the recess on the bit body in which the cutting element is received. The cutting elements are installed in their respective recesses in the bit body, and heat is applied to each cutting clement via a torch to raise the temperature to a point high enough to braze the cutting elements to the bit body in a fixed position but not so high as to damage the PCD layer.

Unfortunately, securing a PDC cutting element to a drill bit restricts the useful life of such cutting element, because the cutting edge of the diamond table and the substrate wear down, creating a so-called “wear flat” and necessitating increased weight-on-bit to maintain a given rate of penetration of the drill bit into the formation due to the increased surface area presented. In addition, unless the cutting element is heated to remove it from the bit and then rebrazed with an unworn portion of the cutting edge presented for engaging a formation, more than half of the cutting element is never used.

Rotatable cutting elements mounted for rotation about a longitudinal axis of the cutting element can wear more evenly than fixed cutting elements, and exhibit a significantly longer useful life without removal from the drill bit. That is, as a cutting element rotates in a bit body, different parts of the cutting edges or surfaces may be exposed at different times, such that more of the cutting element is used. Thus, rotatable cutting elements may have a longer life than fixed cutting elements.

BRIEF SUMMARY

In some embodiments, an earth-boring tool for removing subterranean formation material in a wellbore comprises a tool body and a rotatable cutting element assembly. The rotatable cutting element assembly comprises a cutting element, a sleeve, and a positioning feature. The cutting element comprises a substrate and a table of a polycrystalline hard material secured to the substrate. The table has a front cutting face and a central axis extending through a center of the front cutting face. The sleeve is fixed to the tool body and comprises a cavity having a central axis extending through a center thereof. A portion of the substrate of the cutting element is disposed within the cavity of the sleeve. The positioning feature is disposed within the cavity of the sleeve and at least partially encircles the portion of the substrate disposed within the cavity of the sleeve. The positioning feature is configured to radially offset the central axis of the table from the central axis of the sleeve. The cutting element is rotatable about the central axis of the table within the cavity of the sleeve, and the cutting element and positioning feature are rotatable within the cavity of the sleeve such that the central axis of the table revolves about the central axis of the sleeve.

In other embodiments, a cutting element assembly comprises a sleeve and a cutting element. The sleeve comprises a cavity having a central axis extending through a center thereof. The cutting element comprises a table of polycrystalline hard material secured to a substrate. At least a portion of the substrate is encircled by the cavity of the sleeve. The table has a front cutting face and a central axis extending through a center of the front cutting face and radially offset from the central axis of the sleeve.

In yet other embodiments, a method of using a rotatable cutting element comprises engaging a cutting element of a cutting element assembly with a subterranean formation. The cutting element assembly comprises the cutting element including a table of polycrystalline hard material secured to a substrate and a central axis extending through a center of a front cutting face of the table. The cutting element assembly further comprises a sleeve extending circumferentially about at least a portion of the substrate and having a central axis extending centrally therethrough. The central axis of the cutting element extends parallel to and radially offset from the central axis of the sleeve. The method further comprising rotating the cutting element about the central axis thereof and rotating the cutting element within the sleeve such that the central axis of the cutting element revolves about the central axis of the sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming embodiments of the present disclosure, the advantages of embodiments of the disclosure may be more readily ascertained from the following description of embodiments of the disclosure when read in conjunction with the accompanying drawings in which:

FIG. 1 illustrates an earth-boring tool according to embodiments of the present disclosure;

FIG. 2 is a cross-sectional side view of a cutting element assembly according to embodiments of the present disclosure;

FIG. 3 is a cross-sectional top view of the cutting element assembly of FIG. 2;

FIG. 4 is an exploded view of a cutting element assembly according to embodiments of the present disclosure;

FIGS. 5 and 6 are cross-sectional side views of the cutting element assembly of FIG. 4 in a compressed position and an expanded position, respectively, according to embodiments of the present disclosure; and

FIG. 7 is a top view of a blade comprising a cutting element assembly operatively coupled to a formation-engaging feature according to embodiments of the present disclosure; and

FIGS. 8 and 9 are cross-sectional side views of the cutting element assembly of FIG. 4 mounted to a tool body according to embodiments of the present disclosure.

DETAILED DESCRIPTION

The illustrations presented herein are not actual views of any particular earth-boring tool, rotatable cutting element assembly or component thereof, but are merely idealized representations employed to describe example embodiments of the present disclosure. The following description provides specific details of embodiments of the present disclosure in order to provide a thorough description thereof. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without employing many such specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional techniques employed in the industry. In addition, the description provided below does not include all elements to form a complete structure or assembly. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. Additional conventional acts and structures may be used. Also note, any drawings accompanying the application are for illustrative purposes only, and are thus not drawn to scale. Additionally, elements common between figures may have corresponding numerical designations.

As used herein, the terms “comprising,” “including,” “containing,” “characterized by,” and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps, but also include the more restrictive terms “consisting of” and “consisting essentially of” and grammatical equivalents thereof.

As used herein, the term “may” with respect to a material, structure, feature, or method act indicates that such is contemplated for use in implementation of an embodiment of the disclosure, and such term is used in preference to the more restrictive term “is” so as to avoid any implication that other compatible materials, structures, features and methods usable in combination therewith should or must be excluded.

As used herein, the term “configured” refers to a size, shape, material composition, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a predetermined way.

As used herein, the singular forms following “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

As used herein, spatially relative terms, such as “beneath,” “below,” “lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,” “right,” and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures.

As used herein, the term “substantially” in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, or even at least 99.9% met.

As used herein, the term “about” used in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter).

As used herein, the term “hard material” means and includes any material having a Knoop hardness value of about 1,000 Kg_(f)/mm² (9,807 MPa) or more. Hard materials include, for example, diamond, cubic boron nitride, boron carbide, tungsten carbide, etc.

As used herein, the term “polycrystalline hard material” means and includes any material comprising a plurality of grains or crystals of the material that are bonded directly together by intergranular bonds. The crystal structures of the individual grains of polycrystalline hard material may be randomly oriented in space within the polycrystalline hard material.

As used herein, the term “earth-boring tool” means and includes any type of bit or tool used for drilling during the formation or enlargement of a wellbore and includes, for example, rotary drill bits, percussion bits, core bits, eccentric bits, bi-center bits, reamers, mills, drag bits, roller-cone bits, hybrid bits, and other drilling bits and tools known in the art.

FIG. 1 is a perspective view of an earth-boring tool according to embodiments of the present disclosure. As illustrated in FIG. 1, the earth-boring tool comprises a fixed-cutter rotary drill bit 10. The drill bit 10 comprises a bit body 12 having a central axis 14 about which the drill bit 10 rotates in operation. The bit body 12 further comprises a plurality of blades 16 extending radially outward from the central axis 14 to a gage 18 of the bit body 12. Outer surfaces 20 of the blades 16 may define at least a portion of what is referred to in the art as the “face” of the drill bit 10. The bit body 12 may comprise internal fluid passageways including a longitudinal bore extending through a shank 22, at least partially through the bit body 12, and to fluid ports 24 located in fluid channels 26 at the face of the bit 10.

A row of cutting element assemblies 100 may be mounted to at least one blade 16. For example, cutting element pockets may be formed in the blades 16, and the cutting element assemblies 100 may be positioned in the cutting element pockets. At least one component of the cutting element assembly 100 may be bonded (e.g., brazed, welded, etc.) to the blades 16. FIGS. 2 and 3 illustrate a cross-sectional side view and a cross-sectional top view of the cutting element assembly 100 taken in a plane 3-3, respectively, according to embodiments of the disclosure.

With continued reference to each of FIGS. 1-3, the cutting element assembly 100 may comprise a sleeve 102 that may be secured (e.g., fixed) to the blade 16. The sleeve 102 comprises a cavity 104 extending centrally and at least partially therethrough. A central axis L₁₀₂ of the sleeve 102 extends centrally through the cavity 104. The sleeve 102 may also comprise a groove 103 formed in an interior sidewall 105 of the cavity 104. The groove 103 may be sized and configured to receive a retaining element 109. The retaining element 109 may encircle one or more components disposed within the cavity 104 and may be configured to retain such components within the sleeve 102. The retaining element 109 may comprise a resilient material and/or may be, for example, an O-ring, a split ring, a beveled retaining ring, a bowed retaining ring, a spiral retaining ring, a Belleville spring, or another retaining element.

The cutting element assembly 100 further comprises a cutting element 106. The cutting element 106 includes a table 107 having a front cutting face 108 that may engage a subterranean formation during operation of the bit 10 and a back side surface 110 that may be secured to an end of a substrate 112. A central axis L₁₀₇ may extend through a center of the front cutting face 108 of the table 107.

The table 107 may be formed from a polycrystalline hard material, such as polycrystalline diamond or polycrystalline cubic boron nitride. The substrate 112 may be formed from a hard material including, but not limited to, steel, steel alloys, metal or metal-alloy-cemented carbide, and any derivatives and combinations thereof. Suitable cemented carbides may contain varying amounts of tungsten carbide (WC), titanium carbide (TiC), tantalum carbide (TaC), and niobium carbide (NbC). Additionally, various binding metals or metal alloys may be included in the substrate 112, such as cobalt, nickel, iron, metal alloys, or mixtures thereof. In the substrate 112, the metal carbide particles are supported within a metallic binder, such as cobalt. In other embodiments, the substrate 112 may be formed of a sintered tungsten carbide composite structure. The sleeve 102 may include a hard material such as one of the hard materials described with regard to the hard material of the substrate 112.

As best illustrated in the cross-sectional views of FIGS. 2 and 3, at least a portion of the substrate 112 may be provided in the cavity 104 of the sleeve 102. The substrate 112 may comprise an upper portion 114 and a lower portion 116. The upper portion 114 may have a diameter greater than a diameter of the lower portion 116. In such embodiments, the sleeve 102 may extend circumferentially about the lower portion 116 of the substrate 112 provided within the cavity 104. Each of the table 107 and the upper portion 114 of the substrate 112 may extend over (e.g., beyond) an upper surface 118 of the sleeve 102. A portion of a lower surface 115 of the upper portion 114 of the substrate 112 may abut against (e.g., contact) and may rotate against the upper surface 118 of the sleeve 102 in operation.

With continued reference to FIGS. 2 and 3, a diameter of the lower portion 116 may be less than a diameter of the cavity 104 of the sleeve 102. In some embodiments, a void space may be provided an outer surface 120 of the lower portion 116 of the substrate 112 and the interior sidewall 105 defining the cavity 104 of the sleeve 102. A positioning feature 124 may be provided in the void space between the lower portion 116 of the substrate 112 and the sleeve 102. The positioning feature 124 may be formed from a hard material such as the hard material previously described herein with regard to the hard material of the substrate 112. The positioning feature 124 may have a volume sufficient to substantially fill a volume of the void space. An interior sidewall 126 of the positioning feature 124 may abut against the outer surface 120 of the lower portion 116 of the substrate 112 and an exterior sidewall 128 of the positioning feature 124 may abut against the interior sidewall 105 of the cavity 104. Each of the table 107 and the upper portion 114 of the substrate 112 may extend over an upper surface 130 of the positioning feature 124. A portion of the lower surface 115 of the upper portion 114 of the substrate 112 may abut against and may rotate against the upper surface 130 of the positioning feature 124 in operation.

In some embodiments and as illustrated in the top view of FIG. 3, the positioning feature 124 extends circumferentially at least partially about the outer surface 120 of the lower portion 116 of the substrate 112. In such embodiments, the positioning feature 124 may comprise a crescent-shaped element as illustrated in FIG. 3. In other embodiments, the positioning feature 124 may extend circumferentially about the entire outer surface 120 of the lower portion 116 of the substrate 112 as explained in further detail with reference to the embodiment of FIGS. 4-6.

The positioning feature 124 is sized and configured to radially offset the central axis L₁₀₇ of the table 107 from the central axis L₁₀₂ of the sleeve 102. Accordingly, while the central axis L₁₀₂ of the sleeve 102 and the central axis L₁₀₇ of the table 107 may extend parallel to each other, the central axis L₁₀₂ and the central axis L₁₀₇ are not coaxial.

Each of the positioning feature 124 and the cutting element 106 may be rotatably mounted within the cavity 104 of the sleeve 102. In operation, the cutting element 106 is configured to rotate within the sleeve 102 and within the positioning feature 124 about the central axis L₁₀₇ and the central axis L₁₀₂ responsive to engagement of the cutting element 106 with the subterranean formation. As the bit 10 may be rotated about the central axis 14 thereof and as the front cutting face 108 and a cutting edge 122 extending about a periphery of the front cutting face 108 engages the formation, contact with the formation by the cutting edge 122 and an adjacent portion of the front cutting face 108 may urge the cutting element 106 to rotate about the central axis L₁₀₇. Accordingly, the cutting element 106 may be referred to herein as a “rotatable cutting element” as the cutting element 106 rotates about the central axis L₁₀₇. Rotation of the cutting element 106 may allow the table 107 to engage the formation using the entire circumference of the cutting edge 122, rather than the same section or segment of the cutting edge 122 if the cutting element 106 was not rotatable within the sleeve 102. This may generate more uniform edge wear on the cutting element 106, reducing the potential for formation of a localized, flat area on the cutting edge 122 of the table 107 and a wear flat on the substrate 112 to the rear of the table 107. As a result, the rotatable cutting element 106 may not wear as quickly in one region and thereby exhibit longer downhole life and increased efficiency. Additionally or alternatively, contact of the cutting edge 122 and an adjacent portion of the front cutting face 108 may urge the cutting element 106 and the positioning feature 124 to rotate within the sleeve 102 about the central axis L₁₀₂ of the sleeve 102. Accordingly, the cutting element 106 may also be referred to herein as an “orbiting cutting element” as the cutting element 106 orbits (e.g., revolves) about the central axis L₁₀₂ of the sleeve 102. Rotation of the cutting element 106 may allow an exposure of the cutting edge 122 relative to an adjacent portion of the bit body 12 to which the cutting element assembly 100 may be mounted to be adjusted during operation of the bit 10 as explained in further detail with reference to FIGS. 8 and 9.

In some embodiments, some of the components of the cutting element assembly 100 may be coated with wear resistant and/or low friction coatings. In some embodiments, one or more of the interior sidewall 105 of the cavity 104, the upper surface 118 of the sleeve 102, the upper surface 130 of the positioning feature 124, the lower surface 115 of the upper portion 114 of the substrate 112, the outer surface 120 of the lower portion 116 of the substrate 112, the interior sidewall 126 of the positioning feature 124, and the exterior sidewall 128 of the positioning feature 124 may be provided with such coatings. The coatings may include low friction coatings and/or wear resistant coatings capable of withstanding downhole conditions, such as, by way of example but not limitation, diamond-like carbon (DLC), soft metals (e.g., materials having relatively lower hardness, copper), dry lube films, etc. The coatings may be positioned on the interface surfaces between one or more of the components where there may be a high potential for increased wear as the cutting element 106 and the positioning feature 124 move (e.g., rotate and/or revolve) within the sleeve 102. In some embodiments, different coatings may be used on different surfaces within the same rotatable cutting element assembly 100, as different coatings may have additional benefits when applied to different surfaces. Additional examples may include any variations of low friction or wear resistant materials.

FIGS. 4-6 illustrate an exploded view and cross-sectional views of a cutting element assembly 200 according to additional embodiments of the present disclosure. The cutting element assembly 200 may comprise a sleeve 202 that may be secured (e.g., fixed) to the blade 16. The sleeve 202 comprises a cavity 204 extending centrally and at least partially therethrough and defined by an interior sidewall 206 of the sleeve 202. A central axis L₂₀₂ may extend centrally through the cavity 204. The sleeve 202 may also comprise an aperture 208 extending between an exterior sidewall 210 and the interior sidewall 206. The aperture 208 may be sized and configured to receive a pin 212 therein. In some embodiments, the sleeve 202 comprises a plurality of apertures 208 circumferentially spaced about the sleeve 202 and a plurality of pins 212 that may extend through respective apertures 208.

The cutting element assembly 200 may further comprise a biasing element 214. As illustrated in FIGS. 5 and 6, the biasing element 214 may be provided within the cavity 204 of the sleeve 202. The biasing element 214 may be provided below a positioning feature 216 and the cutting element 106, each of which may also be disposed within the cavity 204 of the sleeve 202 and may be at least partially (e.g., substantially, entirely) encircled by the sleeve 202. The biasing element 214 may be configured to apply a force to a lower surface 218 of the positioning feature 216 of the cutting element 106. The biasing element 214 may be configured to bias the positioning feature 216 and the cutting element 106 mounted in the positioning feature 216 in an expanded position, as illustrated in FIG. 6. Accordingly, the biasing element 214 may be configured to move (e.g., translate, slide) the cutting element 106 and the positioning feature 216 longitudinally along the central axis L₁₀₇ passing through the center of the table 107 as previously described with reference to FIGS. 2 and 3. Examples of biasing elements that may be used include, but are not limited to, springs, washers (e.g., Bellville washers), compressible fluids, magnetic biasing, resilient materials, or combinations thereof.

The positioning feature 216 may comprise a sleeve 222 having a cavity 224 extending at least partially therethrough. As illustrated in the cross-sectional view of FIGS. 5 and 6, the cavity 224 may be defined by an interior sidewall 226. The cavity 224 may be formed in the sleeve 222 such that when the cutting element 106 may be received therein the central axis L₁₀₇ of the table 107 is radially offset relative to the central axis L₂₀₂ of the sleeve 202. Accordingly, a thickness of the sleeve 222 may vary as the sleeve 222 extends circumferentially about the substrate 112 of the cutting element 106.

The positioning feature 216 may comprise a track 228 extending about an exterior sidewall 240 thereof. The track 228 may be formed of an upper track 228 a and a lower track 228 b. The track 228 may be recessed into a portion of the sleeve 222 as illustrated in FIG. 4. Each of the upper and lower track 228 a, 228 b may be undulating and may comprise alternating protrusions 230 and recesses 232. The pin 212 passing through the sleeve 202 may be engaged with the track 228. The engagement of the pin 212 in the track 228 may be configured to rotate the sleeve 222 and the cutting element 106 disposed within the cavity 224 of the sleeve 222 such that the central axis L₁₀₇ may orbit (e.g., revolve) about the central axis L₂₀₂ of the sleeve 202 as described in further detail with regard to FIGS. 8 and 9.

Grooves 234 may be provided above and below the track 228. The grooves 234 may be sized and configured to receive a sealing element 236 therein. The sealing element 236 may encircle the sleeve 222 and may be configured to form a seal between the positioning feature 216 and the sleeve 202 to prevent drilling mud and formation debris from hindering rotation of the positioning feature 216.

A groove 238 may also be provided within an interior sidewall 226 of the cavity 224. The groove 238 may extend about the circumference of the interior sidewall 226 to encircle the outer surface 120 of the lower portion 116 of the substrate 112 disposed in the positioning feature 216. The groove 234 may be sized and configured to receive a retaining element 235 to retain the cutting element 106 within the positioning feature 216 while permitting the cutting element 106 to rotate within the cavity 224. The retaining element 235 may comprise a resilient material and/or may be, for example, an O-ring, a split ring, a beveled retaining ring, a bowed retaining ring, a spiral retaining ring, a Belleville spring, or another retaining element. Those skilled in the art will readily appreciate that the retention mechanism, such as the groove 238 and retaining element 235, may alternatively comprise any other device or mechanism that enables the cutting element 106 to rotate while simultaneously inhibiting removal of the cutting element 106 from the positioning feature 216 without departing from the scope of the disclosure.

The cutting element assembly 200 may also comprise the cutting element 106. As illustrated in FIGS. 5 and 6, the lower portion 116 of the substrate 112 of the cutting element 106 may be provided within the cavity 224 of the sleeve 222. The upper portion 114 of the substrate 112 and the table 107 may extend over an upper surface 220 of the positioning feature 216 and an upper surface 203 of the sleeve 202. A portion of the lower surface 115 of the upper portion 114 of the substrate 112 may abut against (e.g., contact) and may rotate against the upper surface 220 of the positioning feature 216 and the upper surface 203 of the sleeve 202 in operation.

In some embodiments, some of the components of the cutting element assembly 200 may be coated with wear resistant and/or low friction coatings as previously described herein. In some embodiments, one or more of the interior sidewall 206 of the cavity 204, the upper surface 203 of the sleeve 202, the upper surface 220 of the positioning feature 216, the lower surface 115 of the upper portion 114 of the substrate 112, the outer surface 120 of the lower portion 116 of the substrate 112, the interior sidewall 226 of the positioning feature 216, and the exterior sidewall 240 of the positioning feature 216 may be provided with such coatings.

In operation, as the bit 10 may be rotated about the central axis 14 thereof and as the front cutting face 108 and the cutting edge 122 of the cutting element 106 engage the formation, contact with the formation by the cutting edge 122 and an adjacent portion of the front cutting face 108 may urge the cutting element 106 to rotate about the central axis L₁₀₇ within the cavity 224 of the positioning feature 216. Accordingly, the cutting element 106 may be referred to herein as a “rotatable cutting element,” as previously described herein.

The positioning feature 216 may also enable the cutting element 106 and, more particularly, the central axis L₁₀₇ extending through the center of the table 107 to revolve about the central axis L₂₀₂ of the sleeve 202. The track 228 of the positioning feature 216 may act to at least partially prevent revolutions of the cutting element 106 about the central axis L₂₀₂ and to at least partially enable revolutions of the cutting element 106 about the central axis L₂₀₂. As previously described herein, the biasing element 214 interposed between the lower surface 218 of the positioning feature 216 within the cavity 204 of the sleeve 202 biases the cutting element 106 and the positioning feature 216 in the expanded position. When the cutting edge 122 and an adjacent portion of the front cutting face 108 engage the formation, contact with the formation by the cutting edge 122 and an adjacent portion of the front cutting face 108 may urge the cutting element 106 and the positioning feature 216 into the compressed position by applying a force indirectly on the biasing element 214 sufficient to overcome the constant force applied by the biasing element 214 on the positioning feature 216 and the cutting element 106. When the cutting edge 122 and an adjacent portion of the front cutting face 108 are disengaged with the formation, the biasing element 214 may urge the cutting element 106 and the positioning feature 216 into the expanded position.

As the positioning feature 216 is moved axially between the expanded position and the compressed position, the pin 212 may slide along the track 228 between the offset protrusions 230 and recesses 232 and rotate the positioning feature 216 within the sleeve 202 such that the cutting element 106 disposed within the positioning feature 216 revolves about the central axis L₂₀₂. In particular, as the positioning feature 216 moves between the compressed position to the expanded position, the pin 212 moves between engagement with a recess 232 in the lower track 228 b to a recess 232 in the upper track 228 a by moving upward along a surface between the recess 232 to a crest of the protrusion 230 of the lower track 228 b. As the positioning feature 216 moves between the expanded position to the compressed position, the pin 212 moves between engagement with a recess 232 in the upper track 228 a to a recess 232 in the lower track 228 b by moving downward along a surface between the recess 232 to a crest of the protrusion 230 of the upper track 228 a. As a result, as the positioning feature 216 moves axially to the expanded position and back to the compressed position, the pin 212 moves between adjacent recesses 232 in the lower track 228 b. Accordingly, the positioning feature 216 and the cutting element 106 may be incrementally rotated about the central axis L₂₀₂ of the sleeve 202 and may, therefore, be referred to herein as an “indexing mechanism” as the positioning feature 216 and, more particularly, the track 228 of the positioning feature 216 indexes the amount of rotation of the positioning feature 216 and of the cutting element 106. In view of the foregoing, contact of the cutting edge 122 and an adjacent portion of the front cutting face 108 may urge the cutting element 106 and the positioning feature 124 to rotate about the central axis L₁₀₂ of the sleeve 102. Accordingly, the cutting element 106 may also be referred to herein as an “orbiting cutting element” as the cutting element 106 orbits (e.g., revolves) about the central axis L₂₀₂ of the sleeve 202. Rotation of the cutting element 106 may allow an exposure of the cutting edge 122 relative to an adjacent portion of the bit body 12 to which the cutting element assembly 100 may be mounted to be adjusted during operation of the bit 10 as explained in further detail with reference to FIGS. 8 and 9.

The spacing of the protrusions 230 and recesses 232 in the upper and lower tracks 228 a, 228 b may be selected to provide a predetermined amount of radial positions for the positioning feature 216 and the cutting element 106. By way of example, in some embodiments, there may be eight evenly spaced protrusions 230 and recesses 232 in each of the upper and lower tracks 228 a, 228 b such that the cutting element 106 may be revolved about the sleeve 202 in 45-degree increments. In other embodiments, the protrusions 230 and recesses 232 in each of the upper and lower tracks 228 a, 228 b may be comprise eight unevenly spaces such that the cutting element 106 may be revolved about the sleeve 202 in varying increments. The number of protrusions 230 and recesses 232 and the spacing between adjacent protrusions 230 and recesses 232 may be selected and varied based on the amount of revolution desired of the cutting element 106 within the sleeve 202. Furthermore, the slopes of the surfaces between the recesses 232 and the protrusion 230 may be varied to vary the amount of rotation of the positioning feature 216 achieved as the positioning feature 216 is axially translated between the expanded position and the compressed position as described in U.S. patent application Ser. No. 15/662,626, entitled “Rotatable Cutters and Elements for Use on Earth-Boring Tools in Subterranean Boreholes, Earth-Boring Tools Including Same, and Related Methods,” filed on Jul. 28, 2017, the entire disclosure of which is hereby incorporated herein by this reference.

While the track 228 has been illustrated and described as being provided on and about the positioning feature 216 and the pin 212 has been illustrated and described as being provided through the sleeve 202, in other embodiments, the track 228 may be formed about the interior sidewall 206 of the sleeve 202 and the pins 212 may be provided within openings formed in the positioning feature 216 as described in U.S. patent application Ser. No. 15/662,626, previously incorporated herein by reference.

FIG. 7 is a top view of a blade 16 comprising a cutting element assembly 300 according to other embodiments of the present disclosure. For convenience of explanation, some components of the cutting element assembly 300 and components for driving rotation of one or more components of the cutting element assembly 300 are shown in dashed lines as these elements may not be visible in the top view of FIG. 7, but are included in FIG. 7 for clarity. The cutting element assembly 300 may comprise a sleeve 302 fixed to the blade 16. The sleeve 302 comprises a cavity 304 extending centrally and at least partially therethrough. A central axis L₃₀₂ of the sleeve 302 extends centrally through the cavity 304. As previously described with regard to the sleeve 102, the sleeve 302 may also comprise a groove (not shown) formed in an interior sidewall of the cavity 304. The groove may be sized and configured to receive a retaining element as previously described with reference to the retaining element 109 of the embodiments of FIG. 2 for retaining components of the cutting element assembly 300 within the sleeve 302.

The cutting element assembly 300 may also comprise a positioning feature 306 disposed within the cavity 304. The positioning feature 306 may comprise a sleeve 308 having a cavity 310 formed therein similar to the cavity 224 formed in the positioning feature 216 of the embodiment of FIGS. 4-6. The cutting element 106 may be received and retained at least partially within the cavity 310 of the positioning feature 306.

In some embodiments, an aperture 312 may be formed through the sleeve 302 in which the positioning feature 306 may be received such that an impelling feature 314 may be coupled to (e.g., secured to) the positioning feature 306. The impelling feature 314 may comprise a shaft 316 having a mating surface 318A at a longitudinal end of the shaft 316 opposite a longitudinal end of the shaft 316 coupled to the positioning feature 306.

A formation-engaging feature 320 may be located proximate to (e.g., rotationally behind) the cutting element assembly 300 on a common blade 16 therewith. The formation-engaging feature 320 may comprise a rolling element configured to interact with the formation. The formation-engaging feature 320 may comprise a formation-engaging feature as shown and described in U.S. patent application Ser. No. 15/704,806, entitled “Earth-Boring Tools Including Rotatable Cutting Elements and Formation-Engaging Features that Drive rotation of Such Cutting Elements, and Related Methods,” filed on even date herewith, assigned to the assignee of the present application, the entire disclosure of which is incorporated by this reference. The formation-engaging feature 320 may be rotatably mounted to the blade 16 and may rotate about a central axis L₃₂₀ thereof responsive to frictional forces acting between an exterior sidewall 324 of the formation-engaging feature 320 as the bit 10 is rotated about the central axis 14 thereof. The formation-engaging feature 320 may comprise an impelling feature 326 comprising a shaft 328 having a mating surface 318B. The mating surfaces 318A, 318B of the impelling features 314, 328 may comprise miter gears as illustrated in FIG. 7. The mating surfaces 318A, 318B may be configured to operatively engage the impelling features 314, 328. In other embodiments, mechanisms other than a shaft and gear system may be used to be operatively couple the formation-engaging feature 320 and one or more components of the cutting element assembly 300 such as a flexible draft shaft including a drive cable, belt, or chain, as disclosed in U.S. patent application Ser. No. 15/704,806, entitled “Earth-Boring Tools Including Rotatable Cutting Elements and Formation-Engaging Features that Drive rotation of Such Cutting Elements, and Related Methods,” filed on even date herewith, assigned to the assignee of the present application, the entire disclosure of which was previously incorporated herein by reference.

In operation, as the bit 10 may be rotated about the central axis 14 thereof, the exterior sidewall 324 of the formation-engaging feature 320 may engage the formation, contact with the formation by the exterior sidewall 324 of the formation-engaging feature 320 may urge the formation-engaging feature 320 to rotate about its rotational axis L₃₂₀. As the formation-engaging feature 320 may be operatively coupled to the cutting element assembly 300, rotation of the formation-engaging feature 320 may drive rotation of the cutting element 106. When the formation-engaging feature 320 rotates about the central axis L₃₂₀ thereof, the mating surface 318B may rotate and resultantly rotate the mating surface 318A engaged therewith and the shaft 316 coupled to the positioning feature 306. Accordingly, rotation of the formation-engaging feature 320 may drive rotation of the positioning feature 306 within the sleeve 302. Rotation of the positioning feature 306 rotates the cutting element 106 within the sleeve 302 such that the central axis L₁₀₇ extending through the center of the table 107 revolves about the central axis L₃₀₂ of the sleeve 302.

In operation, as the bit 10 may be rotated about the central axis 14 thereof and as the front cutting face 108 and the cutting edge 122 of the cutting element 106 engage the formation, contact with the formation by the cutting edge 122 and an adjacent portion of the front cutting face 108 may urge the cutting element 106 to rotate about the central axis L₁₀₇ within the cavity 310 of the positioning feature 306. In other embodiments, the cutting element 106 may also be coupled to the impelling feature 314 such that rotation of the formation-engaging feature 320 may also drive rotation of the cutting element 106 as previously described with regard to the rotation of the positioning feature 306. Accordingly, the cutting element 106 may be referred to herein as a “rotatable cutting element,” as previously described herein.

As illustrated in FIGS. 2, 5, and 6, the table 107 may be sized and configured such that the cutting edge 122 may not extend radially beyond an exterior sidewall 101, 210 of the sleeve 102, 202 as the cutting element 106 revolves and/or rotates within the sleeve 102, 202. In such embodiments, a diameter of the table 107 and the upper portion 114 of the substrate 112 may be less than a diameter of the sleeve 102, 202. In other embodiments, the table 107 may be sized and configured such that a portion of the cutting edge 122 may extend radially beyond an exterior sidewall 330 of the sleeve 302 as the cutting element 106 revolves and/or rotates within the sleeve 302 as illustrated in FIG. 7. In such embodiments, at least a portion of the table 107 and the upper portion 114 of the substrate 112 may overhang the sleeve 302.

In some embodiments, the positioning feature 124, 216 and the substrate 112 of the cutting element 106 may be coupled together or integrally formed. Put differently, in some embodiments, the substrate 112 of the cutting element 106 may be sized and configured to substantially fill the volume of the cavity 104, 204 of the sleeve 102, 202. In such embodiments, the cutting element 106 may be formed to be asymmetrical such that the lower portion 116 of the substrate 112 has a central axis extending therethrough, which is not coaxial with the central axis L₁₀₇ of the table 107 formed thereover but is coaxial with the central axis L₁₀₂, L₂₀₂ of the sleeve 102, 202. Accordingly, as the cutting element 106 rotates within the sleeve 102, 202, the central axis L₁₀₇ may revolve about the central axis L₁₀₂, L₂₀₂ of the sleeve 102, 202. In such embodiments, the rotation of the cutting element 106 about the central axis L₁₀₇ and about the central axis L₁₀₂ may be one and the same.

Rotation of the cutting element 106 within the sleeve 102 of the embodiment of FIGS. 2 and 3 and/or the sleeve 202 of the embodiment of FIGS. 4-6 enables the exposure of the cutting element 106 to be varied during operation of the bit 10 as explained with reference to FIGS. 8 and 9. While FIGS. 8 and 9 illustrate cross-sectional views of the cutting element assembly 200 mounted to the bit 10 and, more particularly, to one of the blades 16, the cutting element assembly 100 may be mounted to the bit 10 and may operate similarly. As illustrated in FIGS. 8 and 9, the cutting edge 122 of the table 107 may extend above an adjacent outer surface 20 of the blade 16 by a distance referred to herein as “exposure” 350. The exposure 350 of the cutting element 106 may vary based on the relative radial location of the central axis L₁₀₇ to the central axis L₂₀₂ of the sleeve 202. FIG. 8 illustrates a minimum exposure 350 of the cutting element 106. FIG. 9 illustrates a maximum exposure 350 of the cutting element 106 as the central axis L₁₀₇ has been rotated 180 degrees relative to its position in FIG. 8. As the central axis L₁₀₇ revolves about the central axis L₂₀₂, the exposure 350 is varied during operation of the bit 10. The exposure 350 of the cutting elements 106 may be used to effectively control the “depth of cut” (DOC) or the depth to which the cutting edge 122 extends into the subterranean formation with which the cutting element 106 is engaged.

As known in the art the face of the bit 10 may comprise a cone region, a nose region, and a shoulder region extending successively from adjacent the central axis 12 of the bit 10 and radially outward forward the gage 18. The drill bit 10 may comprise a plurality of cutting element assemblies 100, 200 mounted along the blade 16 such that the cutting element assemblies 100, 200 may be mounted in one or more of the cone region, the nose region, and the shoulder region. Accordingly, the drill bit 10 may be configured such that the DOC of the cutting element 106 may be varied across one or more of the cone region, the nose region, and the shoulder region. In such embodiments, one or more of the cutting elements 106 may have the same exposure or different exposure 350 as another cutting element 106 mounted in the same region or a different region of the bit 10.

By modifying the exposure 350 during operation of the bit 10, the aggressiveness of the bit 10 may be modified during operation of the bit 10. As used herein, the aggressiveness of the bit 10 refers to the relative volume of subterranean formation material being removed by engagement of one of more cutting elements 106 with the formation on each rotation of the drill bit 10. A high aggressiveness refers to a relatively larger volume of subterranean formation material being removed by one or more cutting elements 106 on each rotation of the drill bit 10, while a low aggressiveness refers to a relatively smaller volume of subterranean formation material being removed by one or more cutting elements 106 on each rotation of the drill bit 10.

Drill bit aggressiveness may contribute to the vibration, whirl, and stick-slip for a given weight-on-bit (WOB) and drill bit rotational speed. By controlling exposure 350 of cutting element 106 and other aggressiveness-affecting parameters, the bit 10 may form a smoother borehole, avoid premature damage to the cutting elements 106, and prolong operating life of the earth-boring tool. Further, rotation of the cutting element 106 such that the entire circumference of the cutting edge 122 may be used to engage the formation, rather than the same section or segment of the cutting edge 122 if the cutting element 106 was not rotatable, may generate more uniform edge wear on the cutting element 106, and may prolong the operating life and increased cutting efficiency of the cutting elements 106 and the earth-boring tool.

While the present invention has been described herein with respect to certain illustrated embodiments, those of ordinary skill in the art will recognize and appreciate that it is not so limited. Rather, many additions, deletions, and modifications to the illustrated embodiments may be made without departing from the scope of the invention as claimed, including legal equivalents thereof. In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the invention as contemplated by the inventors. Further, embodiments of the disclosure have utility with different and various tool types and configurations. 

1. An earth-boring tool for removing subterranean formation material in a wellbore, comprising: a tool body; and a rotatable cutting element assembly comprising: a cutting element comprising: a substrate; and a table of a polycrystalline hard material secured to the substrate, the table having a front cutting face and a central axis extending through a center of the front cutting face, a sleeve fixed to the tool body, the sleeve comprising a cavity having a central axis extending through a center thereof, a portion of the substrate of the cutting element disposed within the cavity of the sleeve; and a positioning feature disposed within the cavity of the sleeve and at least partially encircling the portion of the substrate disposed within the cavity of the sleeve, the positioning feature configured to radially offset the central axis of the table from the central axis of the sleeve; wherein the cutting element is rotatable about the central axis of the table within the cavity of the sleeve; wherein the cutting element and the positioning feature are rotatable within the cavity of the sleeve such that the central axis of the table revolves about the central axis of the sleeve.
 2. The earth-boring tool of claim 1, wherein the cutting element is configured to rotate about the central axis of the table and wherein the cutting element and positioning feature are rotatable within the cavity of the sleeve such that the central axis of the table revolves about the central axis of the sleeve responsive to engagement of a cutting edge extending about a periphery of the table of the cutting element with a subterranean formation.
 3. The earth-boring tool of claim 1, wherein the cutting element is rotatable within the positioning feature and the sleeve.
 4. The earth-boring tool of claim 1, wherein the positioning feature entirely encircles the portion of the substrate disposed within the sleeve.
 5. The earth-boring tool of claim 1, wherein the positioning feature comprises an indexing mechanism configured to incrementally revolve the central axis of the table about the central axis of the sleeve.
 6. The earth-boring tool of claim 5, wherein the indexing mechanism comprises a track provided about an exterior sidewall of the positioning feature and a pin extending through an aperture in the sleeve and engaged with the track.
 7. The earth-boring tool of claim 1, wherein at least a portion of the substrate and the table of the cutting element extend over an upper surface of the sleeve.
 8. The earth-boring tool of claim 1, wherein a diameter of the table of the cutting element is less than a diameter of the sleeve.
 9. The earth-boring tool of claim 8, wherein a cutting edge extending about a periphery of the table of the cutting element does not extend radially beyond an exterior sidewall of the sleeve.
 10. A cutting element assembly, comprising: a sleeve comprising a cavity having a central axis extending through a center thereof; and a cutting element comprising a table of polycrystalline hard material secured to a substrate, the table having a front cutting face and a central axis extending through a center of the front cutting face, at least a portion of the substrate encircled by the cavity of the sleeve; wherein the central axis of the table is radially offset from the central axis of the sleeve.
 11. The cutting element assembly of claim 10, further comprising a positioning feature disposed within the cavity of the sleeve and at least partially encircling the portion of the substrate of the cutting element encircled by the cavity of the sleeve, the positioning feature configured to radially offset the central axis of the table from the central axis of the sleeve.
 12. The cutting element assembly of claim 11, wherein the positioning feature is rotatably mounted within the cavity of the sleeve.
 13. The cutting element assembly of claim 10, wherein the cutting element is rotatably mounted within the sleeve such that the cutting element may rotate about at least one of the central axis of the table and the central axis of the sleeve.
 14. The cutting element assembly of claim 11, wherein: the positioning feature comprises a sleeve having a cavity formed therein; the portion of the cutting element encircled by the cavity of the sleeve further encircled by the cavity of the positioning feature; and the sleeve of the positioning feature varying in thickness as the sleeve encircles the cutting element.
 15. A method of using a rotatable cutting element, comprising: engaging a cutting element of a cutting element assembly with a subterranean formation, the cutting element assembly comprising: the cutting element comprising a table of polycrystalline hard material secured to a substrate and a central axis extending through a center of a front cutting face of the table; and a sleeve extending circumferentially about at least a portion of the substrate and having a central axis extending centrally therethrough, the central axis of the cutting element extending parallel to and radially offset from the central axis of the sleeve; rotating the cutting element about the central axis thereof; and rotating the cutting element within the sleeve such that the central axis of the cutting element revolves about the central axis of the sleeve.
 16. The method of claim 15, wherein engaging the cutting element of the cutting element assembly with the subterranean formation comprises engaging a cutting edge extending about a periphery of the front cutting face of the table with the subterranean formation.
 17. The method of claim 16, wherein rotating the cutting element within the sleeve such that the central axis of the cutting element revolves about the central axis of the sleeve comprises varying an exposure of the cutting edge of the cutting element relative to an adjacent outermost surface of a bit body to which the cutting element assembly is secured.
 18. The method of claim 15, wherein rotating the cutting element within the sleeve such that the central axis of the cutting element revolves about the central axis of the sleeve comprises: engaging a formation-engaging feature operatively coupled to the cutting element with the subterranean formation; rotating the formation-engaging feature responsive to engagement with the subterranean formation; and rotating the cutting element within the sleeve responsive to rotation of the formation-engaging feature operatively coupled thereto.
 19. The method of claim 15, wherein the cutting element assembly further comprises a positioning feature provided radially between the substrate and the sleeve, and wherein rotating the cutting element within the sleeve such that the central axis of the cutting element revolves about the central axis of the sleeve comprises rotating the positioning feature within the sleeve.
 20. The method of claim 15, wherein rotating the cutting element about the central axis thereof and rotating the cutting element within the sleeve such that the central axis of the cutting element revolves about the central axis of the sleeve comprises simultaneously rotating the cutting element about the central axis thereof and rotating the cutting element within the sleeve such that the central axis of the cutting element revolves about the central axis of the sleeve. 